The present invention pertains to microbolometer sensors and particularly to detector material for microbolometers. More particularly, the invention pertains to a particular detector material which is fabrication from a special ion beam sputter deposition process. The U.S. Government has certain rights in the present invention.
A major factor in the sensitivity of a bolometer is the TCR (thermal coefficient of resistance) of the detector material. The overall NETD sensitivity of the bolometer also depends on the noise level. Previous bolometer materials are typically high TCR metals with a TCR in the range from 0.003 to 0.004. These materials have low noise but also have low TCR. Since the metals are reflectors, they also degrade the absorbance properties of the detector. Materials which undergo a phase transitions (i.e., Mott transition) can have a very high TCR""s in the transition region but can suffer from a number of problems. First, the latent heat accompanying the phase change for these materials may significantly decrease the sensitivity of the detector. Second, most switching material can be produced in only one form without additional doping, which defines the material resistance and TCR. Further, the temperature range over which the transition occurs is typically very small requiring tight temperature control of the operation. Finally, the films must be produced in crystalline form which requires high temperature depositions.
The present invention is peculiar vanadium oxide (VOx/ABx) (i.e., VOx/ABx) detector material and process that is used to make that material. The x of VOx is a value fitting for the pixel being sputter deposited by the present process and is not necessarily a specific digit such as xe2x80x9c2xe2x80x9d, but may be between 1 and 2.5. That material is deposited as part of a pixel for a high performance microbolometer. The material is deposited by an ion beam sputtering with control of the deposition process leading to a flexible detector process for microbolometer detectors. These detector materials have optical, electrical, and thermal properties compatible with high performance detectors but which can be readily modified to suit individual requirements of an array design.